In general, a network communication device such as the LAN switches or the routers includes a circuit board unit having an interface function for packet transfer, a circuit board unit having a function of switching a packet to a desired port, and a circuit board unit having a function of controlling the packet transfer. Those circuit board units are connected to a relay circuit board (so-called backplane) arranged within the device through a connector, and signal transfer and power feeding between the circuit board units are executed through the backplane.
As a power supply of the network communication device, AC 100V or AC 200V is frequently applied in AC devices, and DC 48 V is frequently applied in DC devices. In general, the voltage is input to a front power unit of the device, the front power unit outputs DC 48 V, and the DC 48 V output is supplied to the respective circuit board units through the backplane.
On the other hand, an information processing device represented by the servers is also unitized into circuit board units for each function, as with the LAN switches and the routers. Those circuit board units are connected to the backplane arranged within the device through the connector, and the signal transfer and the power feeding between the circuit board units are executed through the backplane.
The power supply of the server is frequently AC 100V or AC 200V. In general, this voltage is input to the front power unit of the device, the front power unit outputs DC 12 V, and the DC 12 V output is applied to the respective circuit board units through the backplane.
Also, as a cooling structure of the network communication device and the information processing device, a cooling structure of an anteroposterior intake and exhaust system complying with an NEBS (network equipment building system) which is a standard of communication devices for communication carriers has been increasingly demanded.
In PTL 1, with higher function and multiple functions of electronic devices such as the servers, the number of electronic components to be mounted is exponentially increased, resulting in an increase in a current necessary for operating the electronic devices. Simultaneously, the electronic devices have been increasingly downsized and reduced in weight, and a demand for the reduction in the size and weight of the electronic components has also been increased. Accordingly, it is desirable to provide a feed bus bar structure that enables a large current to flow therein with a small size. However, there arises such a problem that the feed bus bar is heated by allowing the large current to flow therein.
In order to solve the above problem, The above PTL 1 employs a structure in which power supplies and loads are connected to each other one-on-one with the use of a bar-shaped feed bus bar, and a cooling fin is disposed in the feed bus bar to forcedly cool the feed bus bar.
Also, in PTL 2, when a large current is supplied to a circuit board unit within an electronic device, in power feeding using a usual connector, there is a need to increase the number of power supply connector pins, or decrease the number of signal connector pins to shift to the power supply purpose.
In order to solve the above problem, the above PTL 2 employs a connector structure in which a bar-shaped feed bar having a plurality of conductive layers and insulating layers like a multilayer circuit board is fixed to a gap between connectors of the backplane by a conductive pin contact and a conductive spacer, and the conductive pin contact and the circuit board unit are electrically connected to each other to supply the large current.
Further, in recent years, apart from the problems to be solved by the above PTL 1 and PTL 2, a new problem described below is actualized in the backplane structure of the electronic device.
As a first background, in a main system of the power feeding in the network communication device, DC 48 V is applied to the respective circuit board units through the backplane. However, in recent years, a shift from the 48 V feed system to a 12 V feed system is advanced. This is mainly because the 48 V feed system is large in configuration, needs to use an expensive insulating DC/DC converter, and is disadvantageous in power efficiency of the feed system and the installation area within the circuit board unit. On the other hand, in order to supply the same electric power as that of the 48 V feed system, the 12 V feed system needs to allow a current of four times to flow.
As a second background, in recent years, as the cooling structure of the network communication device and the information processing device, the cooling structure of the anteroposterior intake and exhaust system complying with the NEBS (network equipment building system) which is the standard of the communication devices for the communication carriers has been increasingly demanded. As the network communication device of the anteroposterior intake and exhaust system, configurations illustrated in FIGS. 1(a) to 4(a) are proposed. In order to realize the anteroposterior intake and exhaust system, there is a need to form a ventilator through which a cooling air passes in the backplane.